scholarly journals Impact of the Baloxavir-Resistant Polymerase Acid I38T Substitution on the Fitness of Contemporary Influenza A(H1N1)pdm09 and A(H3N2) Strains

2019 ◽  
Vol 221 (1) ◽  
pp. 63-70 ◽  
Author(s):  
Liva Checkmahomed ◽  
Zeineb M’hamdi ◽  
Julie Carbonneau ◽  
Marie-Christine Venable ◽  
Mariana Baz ◽  
...  
Keyword(s):  
Influenza A ◽  
Mdck Cells ◽  
Influenza Viruses ◽  
Recombinant Viruses ◽  
Influenza A H1n1 ◽  
2009 H1n1 ◽  
Similar Weight ◽  
Viral Subtypes ◽  
The Impact

Abstract Background Baloxavir is a cap-dependent inhibitor of the polymerase acid (PA) protein of influenza viruses. While appearing virologically superior to oseltamivir, baloxavir exhibits a low barrier of resistance. We sought to assess the impact of the common baloxavir-resistant I38T PA substitution on in vitro properties and virulence. Methods Influenza A/Quebec/144147/2009 (H1N1)pdm09 and A/Switzerland/9715293/2013 (H3N2) recombinant viruses and their I38T PA mutants were compared in single and competitive infection experiments in ST6GalI-MDCK cells and C57/BL6 mice. Virus titers in cell culture supernatants and lung homogenates were determined by virus yield assays. Ratios of wild-type (WT) and I38T mutant were assessed by digital RT-PCR. Results I38T substitution did not alter the replication kinetics of A(H1N1)pdm09 and A(H3N2) viruses. In competition experiments, a 50%:50% mixture evolved to 70%:30% (WT/mutant) for A(H1N1) and 88%:12% for A(H3N2) viruses after a single cell passage. The I38T substitution remained stable after 4 passages in vitro. In mice, the WT and its I38T mutant induced similar weight loss with comparable lung titers in both viral subtypes. The mutant virus tended to predominate over the WT in mouse competition experiments. Conclusion The fitness of baloxavir-resistant I38T PA mutants appears relatively unaltered in seasonal subtypes warranting surveillance for its dissemination.

scholarly journals Antigenic Drift of the Influenza A(H1N1)pdm09 Virus Neuraminidase Results in Reduced Effectiveness of A/California/7/2009 (H1N1pdm09)-Specific Antibodies

mBio ◽  
2019 ◽  
Vol 10 (2) ◽  
Author(s):  
Jin Gao ◽  
Laura Couzens ◽  
David F. Burke ◽  
Hongquan Wan ◽  
Patrick Wilson ◽  
...  
Keyword(s):  
Monoclonal Antibodies ◽  
Influenza Viruses ◽  
Antigenic Drift ◽  
Influenza Vaccines ◽  
Vaccine Production ◽  
Antigenic Sites ◽  
Vaccine Component ◽  
Influenza A H1n1 ◽  
The Impact

ABSTRACTThe effectiveness of influenza vaccines against circulating A(H1N1)pdm09 viruses was modest for several seasons despite the absence of antigenic drift of hemagglutinin (HA), the primary vaccine component. Since antibodies against HA and neuraminidase (NA) contribute independently to protection against disease, antigenic changes in NA may allow A(H1N1)pdm09 viruses to escape from vaccine-induced immunity. In this study, analysis of the specificities of human NA-specific monoclonal antibodies identified antigenic sites that have changed over time. The impact of these differences onin vitroinhibition of enzyme activity was not evident for polyclonal antisera until viruses emerged in 2013 without a predicted glycosylation site at amino acid 386 in NA. Phylogenetic and antigenic cartography demonstrated significant antigenic changes that in most cases aligned with genetic differences. Typical of NA drift, the antigenic difference is observed in one direction, with antibodies against conserved antigenic domains in A/California/7/2009 (CA/09) continuing to inhibit NA of recent A(H1N1)pdm09 viruses reasonably well. However, ferret CA/09-specific antiserum that inhibited the NA of A/Michigan/45/2015 (MI/15) very wellin vitro, protected mice against lethal MI/15 infection poorly. These data show that antiserum against the homologous antigen is most effective and suggest the antigenic properties of NA should not be overlooked when selecting viruses for vaccine production.IMPORTANCEThe effectiveness of seasonal influenza vaccines against circulating A(H1N1)pdm09 viruses has been modest in recent years, despite the absence of antigenic drift of HA, the primary vaccine component. Human monoclonal antibodies identified antigenic sites in NA that changed early after the new pandemic virus emerged. The reactivity of ferret antisera demonstrated antigenic drift of A(H1N1)pdm09 NA from 2013 onward. Passive transfer of serum raised against A/California/7/2009 was less effective than ferret serum against the homologous virus in protecting mice against a virus with the NA of more recent virus, A/Michigan/45/2015. Given the long-standing observation that NA-inhibiting antibodies are associated with resistance against disease in humans, these data demonstrate the importance of evaluating NA drift and suggest that vaccine effectiveness might be improved by selecting viruses for vaccine production that have NAs antigenically similar to those of circulating influenza viruses.

scholarly journals In Vitro Antiviral Activity of Favipiravir (T-705) against Drug-Resistant Influenza and 2009 A(H1N1) Viruses

2010 ◽  
Vol 54 (6) ◽  
pp. 2517-2524 ◽  
Author(s):  
Katrina Sleeman ◽  
Vasiliy P. Mishin ◽  
Varough M. Deyde ◽  
Yousuke Furuta ◽  
Alexander I. Klimov ◽  
...  
Keyword(s):  
Influenza A ◽  
Seasonal Influenza ◽  
Mdck Cells ◽  
Antiviral Effect ◽  
Plaque Formation ◽  
Influenza Viruses ◽  
New Drugs ◽  
Yield Reduction ◽  
Wide Range

ABSTRACT Favipiravir (T-705) has previously been shown to have a potent antiviral effect against influenza virus and some other RNA viruses in both cell culture and in animal models. Currently, favipiravir is undergoing clinical evaluation for the treatment of influenza A and B virus infections. In this study, favipiravir was evaluated in vitro for its ability to inhibit the replication of a representative panel of seasonal influenza viruses, the 2009 A(H1N1) strains, and animal viruses with pandemic (pdm) potential (swine triple reassortants, H2N2, H4N2, avian H7N2, and avian H5N1), including viruses which are resistant to the currently licensed anti-influenza drugs. All viruses were tested in a plaque reduction assay with MDCK cells, and a subset was also tested in both yield reduction and focus inhibition (FI) assays. For the majority of viruses tested, favipiravir significantly inhibited plaque formation at 3.2 μM (0.5 μg/ml) (50% effective concentrations [EC50s] of 0.19 to 22.48 μM and 0.03 to 3.53 μg/ml), and for all viruses, with the exception of a single dually resistant 2009 A(H1N1) virus, complete inhibition of plaque formation was seen at 3.2 μM (0.5 μg/ml). Due to the 2009 pandemic and increased drug resistance in circulating seasonal influenza viruses, there is an urgent need for new drugs which target influenza. This study demonstrates that favipiravir inhibits in vitro replication of a wide range of influenza viruses, including those resistant to currently available drugs.

scholarly journals Real-time estimation of the hospitalization fatality risk of influenza A(H1N1)pdm09 in Hong Kong

2015 ◽  
Vol 144 (8) ◽  
pp. 1579-1583
Author(s):  
J. Y. WONG ◽  
P. WU ◽  
E. H. Y. LAU ◽  
T. K. TSANG ◽  
V. J. FANG ◽  
...  
Keyword(s):  
Hong Kong ◽  
Real Time ◽  
Influenza A ◽  
Early Stage ◽  
Influenza Pandemic ◽  
Influenza Viruses ◽  
Right Censoring ◽  
Fatality Risk ◽  
Influenza A H1n1 ◽  
The Impact

SUMMARYDuring the early stage of an epidemic, timely and reliable estimation of the severity of infections are important for predicting the impact that the influenza viruses will have in the population. We obtained age-specific deaths and hospitalizations for patients with laboratory-confirmed H1N1pdm09 infections from June 2009 to December 2009 in Hong Kong. We retrospectively obtained the real-time estimates of the hospitalization fatality risk (HFR), using crude estimation or allowing for right-censoring for final status in some patients. Models accounting for right-censoring performed better than models without adjustments. The risk of deaths in hospitalized patients with confirmed H1N1pdm09 increased with age. Reliable estimates of the HFR could be obtained before the peak of the first wave of H1N1pdm09 in young and middle-aged adults but after the peak in the elderly. In the next influenza pandemic, timely estimation of the HFR will contribute to risk assessment and disease control.

scholarly journals Natural Variation Can Significantly Alter the Sensitivity of Influenza A (H5N1) Viruses to Oseltamivir

2006 ◽  
Vol 50 (11) ◽  
pp. 3809-3815 ◽  
Author(s):  
M. A. Rameix-Welti ◽  
F. Agou ◽  
P. Buchy ◽  
S. Mardy ◽  
J. T. Aubin ◽  
...  
Keyword(s):  
Influenza A ◽  
Influenza Pandemic ◽  
Fold Increase ◽  
Influenza Viruses ◽  
Control Measures ◽  
Inhibition Assay ◽  
Highly Pathogenic ◽  
H5n1 Influenza ◽  
The Impact

ABSTRACT Geographic spread of highly pathogenic avian H5N1 influenza viruses may give rise to an influenza pandemic. During the first months of a pandemic, control measures would rely mainly on antiviral drugs, such as the neuraminidase (NA) inhibitors oseltamivir and zanamivir. In this study, we compare the sensitivities to oseltamivir of the NAs of several highly pathogenic H5N1 viruses isolated in Asia from 1997 to 2005. The corresponding 50% inhibitory concentrations were determined using a standard in vitro NA inhibition assay. The Km for the substrate and the affinity for the inhibitor (Ki ) of NA were determined for a 1997 and a 2005 virus, using an NA inhibition assay on cells transiently expressing the viral enzyme. Our data show that the sensitivities of the NAs of H5N1 viruses isolated in 2004 and 2005 to oseltamivir are about 10-fold higher than those of earlier H5N1 viruses or currently circulating H1N1 viruses. Three-dimensional modeling of the N1 protein predicted that Glu248Gly and Tyr252His changes could account for increased sensitivity. Our data indicate that genetic variation in the absence of any drug-selective pressure may result in significant variations in sensitivity to anti-NA drugs. Although the clinical relevance of a 10-fold increase in the sensitivity of NA to oseltamivir needs to be investigated further, the possibility that sensitivity to anti-NA drugs could increase (or possibly decrease) significantly, even in the absence of treatment, underscores the need for continuous evaluation of the impact of genetic drift on this parameter, especially for influenza viruses with pandemic potential.

scholarly journals Influenza vaccine effectiveness against laboratory-confirmed influenza in hospitalised adults aged 60 years or older, Valencia Region, Spain, 2017/18 influenza season

2019 ◽  
Vol 24 (31) ◽  
Author(s):  
Ainara Mira-Iglesias ◽  
F Xavier López-Labrador ◽  
Víctor Baselga-Moreno ◽  
Miguel Tortajada-Girbés ◽  
Juan Mollar-Maseres ◽  
...  
Keyword(s):  
Influenza Vaccine ◽  
Influenza A ◽  
Vaccine Effectiveness ◽  
Influenza Viruses ◽  
Influenza B ◽  
Current Season ◽  
Hospitalised Patients ◽  
Influenza A H1n1 ◽  
Vaccine Type ◽  
The Impact

Introduction Influenza immunisation is recommended for elderly people each season. The influenza vaccine effectiveness (IVE) varies annually due to influenza viruses evolving and the vaccine composition. Aim To estimate, in inpatients ≥ 60 years old, the 2017/18 trivalent IVE, overall, by vaccine type and by strain. The impact of vaccination in any of the two previous seasons (2016/17 and 2015/16) on current (2017/18) IVE was also explored. Methods This was a multicentre prospective observational study within the Valencia Hospital Surveillance Network for the Study of Influenza and Respiratory Viruses Disease (VAHNSI, Spain). The test-negative design was applied taking laboratory-confirmed influenza as outcome and vaccination status as main exposure. Information about potential confounders was obtained from clinical registries and/or by interviewing patients; vaccine information was only ascertained by registries. Results Overall, 2017/18 IVE was 9.9% (95% CI: −15.5 to 29.6%), and specifically, 48.3% (95% CI: 13.5% to 69.1%), −29.9% (95% CI: −79.1% to 5.8%) and 25.7% (95% CI: −8.8% to 49.3%) against A(H1N1)pdm09, A(H3N2) and B/Yamagata lineage, respectively. For the adjuvanted and non-adjuvanted vaccines, overall IVE was 10.0% (95% CI: −24.4% to 34.9%) and 7.8% (95% CI: −23.1% to 31.0%) respectively. Prior vaccination significantly protected against influenza B/Yamagata lineage (IVE: 50.2%; 95% CI: 2.3% to 74.6%) in patients not vaccinated in the current season. For those repeatedly vaccinated against influenza A(H1N1)pdm09, IVE was 46.4% (95% CI: 6.8% to 69.2%). Conclusion Our data revealed low vaccine effectiveness against influenza in hospitalised patients ≥60 years old in 2017/18. Prior vaccination protected against influenza A(H1N1)pdm09 and B/Yamagata-lineage.

Replication and transmission of an influenza A(H3N2) virus harboring the polymerase acidic I38T substitution, in guinea pigs.

2021 ◽  
Vol 102 (10) ◽  
Author(s):  
Zeineb Mhamdi ◽  
Julie Carbonneau ◽  
Marie-Christine Venable ◽  
Mariana Baz ◽  
Yacine Abed ◽  
...  
Keyword(s):  
Guinea Pigs ◽  
Influenza A ◽  
Reverse Genetics ◽  
Mdck Cells ◽  
A549 Cells ◽  
Viral Fitness ◽  
Viral Population ◽  
H3n2 Virus ◽  
The Impact

The polymerase acidic (PA) I38T substitution is a dominant marker of resistance to baloxavir. We evaluated the impact of I38T on the fitness of a contemporary influenza A(H3N2) virus. Influenza A/Switzerland/9715293/2013 (H3N2) wild-type (WT) virus and its I38T mutant were rescued by reverse genetics. Replication kinetics were compared using ST6GalI-MDCK and A549 cells and infectivity/contact transmissibility were evaluated in guinea pigs. Nasal wash (NW) viral titres were determined by TCID50 ml−1 in ST6GalI-MDCK cells. Competition experiments were performed and the evolution of viral population was assessed by droplet digital RT-PCR. I38T did not alter in vitro replication. I38T induced comparable titres vs the WT in guinea pigs NWs and the two viruses transmitted equally by direct contact. However, a 50 %:50 % mixture inoculum evolved to mean WT/I38T ratios of 71 %:29 % and 66.4 %:33.6 % on days 4 and 6 p.i., respectively. Contemporary influenza A(H3N2)-I38T PA variants may conserve a significant level of viral fitness.

scholarly journals Synergistic Antiviral Activity of S-033188/S-033447, a Novel Inhibitor of Influenza Virus Cap-Dependent Endonuclease, in Combination with Neuraminidase Inhibitors In Vitro

2017 ◽  
Vol 4 (suppl_1) ◽  
pp. S371-S371 ◽  
Author(s):  
Mitsutaka Kitano ◽  
Atsuko Yamamoto ◽  
Takeshi Noshi ◽  
Makoto Kawai ◽  
Ryu Yoshida ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Influenza A ◽  
Cultured Cells ◽  
H1n1 Virus ◽  
Mdck Cells ◽  
Active Form ◽  
Neuraminidase Inhibitors ◽  
Dependent Endonuclease ◽  
Influenza A H1n1

Abstract Background S-033447, an active form of orally available prodrug S-033188, is a novel small molecule inhibitor of cap-dependent endonuclease that is essential for influenza virus transcription and replication. In this study, we evaluated the inhibitory effect of S-033188 in combination with neuraminidase inhibitors on the replication of influenza A/H1N1 virus in cultured cells. Methods The inhibitory effects of S-033447 in combination with NA inhibitors on the cytopathic effect of A/PR/8/34 strain in Madin–Darby canine kidney cells cultured for 2 days were tested and EC50 were determined. The combination index (CI), which were obtained when S-033188 and NA inhibitor were added at the closest ratio of each EC50 value, were used for the evaluation of these combinational effects (Table 1). CI values were calculated by the Chou and Talalay method, in which combinational effect were determined according to the criteria as follows: synergistic if CI ≤ 0.8, additive if 0.8 < CI < 1.2, and antagonistic if CI ≥ 1.2. CI = (DA/A + B)/DA + (DB/A + B)/DB + (DA/A + B × DB/A + B)/(DA × DB) DA: the EC50 of S-033447 DB: the EC50 of NA inhibitor DA/A + B: the concentration of S-033447 giving 50% inhibition in combination with NA inhibitor at the closest ratio of each EC50 value DB/A + B: the concentration of NA inhibitor giving 50% inhibition in combination with S-033447 at the closest ratio of each EC50 value Results All CI values were lower than 0.8, under the condition that both S-033447 and NA inhibitor (oseltamivir acid, zanamivir hydrate, laninamivir, or peramivir trihydrate) were added at the closest ratio of each EC50 value (Table 1). Conclusion S-033447 in combination with oseltamivir acid, zanamivir hydrate, laninamivir, or peramivir trihydrate synergistically inhibited the replication of influenza A/H1N1 virus in MDCK cells. Disclosures All authors: No reported disclosures.

scholarly journals In Vitro Properties and Virulence of Contemporary Recombinant Influenza B Viruses Harboring Mutations of Cross-Resistance to Neuraminidase Inhibitors

Viruses ◽  
2018 ◽  
Vol 11 (1) ◽  
pp. 6 ◽  
Author(s):  
Clément Fage ◽  
Yacine Abed ◽  
Liva Checkmahomed ◽  
Marie-Christine Venable ◽  
Guy Boivin
Keyword(s):  
Influenza A ◽  
Mdck Cells ◽  
Viral Fitness ◽  
World Health ◽  
Cross Resistance ◽  
Influenza B ◽  
Neuraminidase Inhibitors ◽  
Clinical Markers ◽  
The Impact

Three neuraminidase inhibitors (NAIs: Oseltamivir, zanamivir and peramivir) are currently approved in many countries for the treatment of influenza A and B infections. The emergence of influenza B viruses (IBVs) containing mutations of cross-resistance to these NAIs constitutes a serious clinical threat. Herein, we used a reverse genetics system for the current B/Phuket/3073/2013 vaccine strain to investigate the impact on in vitro properties and virulence of H136N, R152K, D198E/N, I222T and N294S NA substitutions (N2 numbering), reported by the World Health Organization (WHO) as clinical markers of reduced or highly-reduced inhibition (RI/HRI) to multiple NAIs. Recombinant viruses were tested by NA inhibition assays. Their replicative capacity and virulence were evaluated in ST6GalI-MDCK cells and BALB/c mice, respectively. All NA mutants (excepted D198E/N) showed RI/HRI phenotypes against ≥ 2 NAIs. These mutants grew to comparable titers of the recombinant wild-type (WT) IBV in vitro, and some of them (H136N, I222T and N294S mutants) induced more weight loss and mortality in BALB/c mice in comparison to the recombinant WT IBV. These results demonstrate that, in contemporary IBVs, some NA mutations may confer RI/HRI phenotypes to existing NAIs without altering the viral fitness. This reinforces the need for development of novel antiviral strategies with different mechanisms of action.

In vitro Inhibitory Effects of Combinations of anti-Influenza Agents

1995 ◽  
Vol 6 (2) ◽  
pp. 109-113 ◽  
Author(s):  
L. K. Madren ◽  
C. Shipman ◽  
F. G. Hayden
Keyword(s):  
Viral Replication ◽  
Influenza A ◽  
H1n1 Virus ◽  
Mdck Cells ◽  
Clinical Isolates ◽  
H1n1 Subtype ◽  
Additive Effects ◽  
Inhibitory Effects ◽  
Influenza A H1n1

To assess the possible interactions among candidate anti-influenza agents, dual combinations of rimantadine, ribavirin, 2′-deoxy-2′-fluoroguanosine (2-FDG) and 4-guanidino-Neu5Ac2en (GG167) were tested against clinical isolates of influenza A H3N2 and H1N1 subtype viruses in MDCK cells by ELISA. Each of the dual combinations showed additive effects, except for the combination of 2-FDG and ribavirin which was synergistic against the influenza A (H1N1) virus. However, this combination also showed enhanced cytotoxicity. In this assay system, influenza agents with differing mechanisms of antiviral interaction interacted in an additive fashion with respect to inhibition of viral replication.

scholarly journals Selenium Nanoparticles Inhibited H1N1 Influenza Virus Induced Apoptosis By Improving The Level of Gpx1

2021 ◽  
Author(s):  
Xia Liu ◽  
Danyang Chen ◽  
Jingyao Su ◽  
Rulin Zheng ◽  
Zhihui Ning ◽  
...  
Keyword(s):  
Influenza A ◽  
Mdck Cells ◽  
Influenza Infection ◽  
Chromatin Condensation ◽  
H1n1 Influenza ◽  
Influenza Viruses ◽  
Selenium Nanoparticles ◽  
Influenza A H1n1 ◽  
Mechanistic Investigation ◽  
Induced Apoptosis

Abstract Influenza A (H1N1) viruses are distributed around the world and pose a threat to public health. Vaccination is the main treatment strategy to prevent influenza infection, but antiviral drugs also play an important role in controlling seasonal and pandemic influenza. Currently, influenza viruses may emerge antiviral resistance, new agents with different modes of action are being investigated. Recently, selenium nanoparticles (SeNPs) which have antiviral effects attracted more and more attention in biomedical interventions. The appearance of nanotechnology attract great attention in the nanomedicine field. SeNPs constitute an attractive vector platform for delivering a variety of drugs to action targets. SeNPs is being explored for potential therapeutic efficacy in a variety of oxidative stress and inflammation-mediated diseases, such as cancer, arthritis, diabetes, and kidney disease. SeNPs could inhibit infection of Madin Darby Canine Kidney (MDCK) cells with H1N1 and prevent chromatin condensation and DNA fragmentation. ROS play a key role in physiological processes on apoptosis. SeNPs significantly inhibited the production of reactive oxygen species (ROS) in MDCK cells. Mechanistic investigation revealed that SeNPs inhibited the apoptosis induced by H1N1 virus infection in MDCK cells by improving the level of GPx1. Our results suggest that SeNPs is an effective selenium source to obtain H1N1 influenza antiviral candidate.

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